Field of Invention
This invention relates to a semiconductor process, and particularly relates to a semiconductor process capable of reducing contact resistance, and a semiconductor device that can be formed with the semiconductor process.
Description of Related Art
In the strained silicon technology for MOS transistors, a source/drain region of an NMOS transistor usually includes a strained silicon-phosphorus (SiP) epitaxial layer. A metal silicide is usually formed over the SiP layer to reduce the contact resistance.
In a conventional process, the metal silicide is not formed until a contact hole is formed over and exposing the SiP epitaxial layer. Since SiP is easily oxidized during the period, native oxide is easily formed on the SiP epitaxial layer separating the same from the metal silicide, so that the contact resistance is raised.